Angles 1&3 are vertically opposite angles so they would be equal
Angles 3&4 are alternate interior angles and would also be equal
Angles 1&2 and 2&3 are angles on a straight line so they would add to 180°
Angles 1&4 are corresponding angles and would be equal.
Since angle 1&2 add to 180
180-81=99
So angle 2 is 99°
Angles 1&3 are vertically opposite would be equal so angle 3 is 81°
Angles 1&4 are corresponding so angle 4 is 81°
I hope this helps :)